Attachment for telephones.



R. E. PEDIGO. ATTACHMENT FOR TELEPHONES. APPLICATION FILED JULY 13, 190B;

Patented 5 1 .118 8,

a v einuenfoz RICHARD E. PEDIGO, OF CHARITON, IOWA.

ATTACHMENT FOR TELEPHONES.

' Specification of Letters Patent.

Patented June 8, 1909.

Application filed July 13, 1908. Serial No. 443,309.

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Be it known that I, liicimnn E. Pnnltio, a

citizen of the United States, residing at (.harit n. in the county of Lucas and State hooker off the hook there will he no dithculty in sending signalsover the line.

of low a have invented a new and uscliul Attachnient for 'llelephoncs, of which the followingis a specification.

This invention has reference to iinproveliitlltS lll attachments for telephones and T he present invention is designed as an attachment for ordinary existing, telephone already installed in telephone lines'and which attachments may be inserted by persons unskilled in the installation of telephone more particularly for use in connection with g niultipart v telephone lines.

in inultipart v lines and more particu- I larly in rural districts the sending of a signal over a line results in a number of the sub-- scribers removing their receivers from the receiver hooks. Under such circumstances. it the proper subscriber does not respond to the call it becomes practically impossible to send another call over the line. because ol the fact i that the signal will traverse the receiver coils of those receivers which have been reniovcd from their hooks. l ndcr such circumstances, the calling station must await the replacing ol' the removed receivers on the hooks before the proper signal can be repeated, and this procedure is not onl annoyingbut time consuming.

it is the object of the present invention to provide a means whereby the removal ol any or all the receivers from the receiver hooks in a inulti party line will not iiitcrl crc with the transmission of signal currents over the line and the reception thereof by the' 'iropcr subscribefls set.

The coils of the signal hells are usually of high resistance and the nurgnetos are suitably designed to generate a current of sulliciently high voltage to properly energize the coils of the signal hells. To such a current the coils of the receivers present low resistance so that when the telephone receiver is oil' the hook and no longer cut. out by lhc contact controlled by the hook, then the path through the receiver will shunt so much of thc magneto current that the bells will not respond, so that it is practically impossible to send a signal over the lino when the receivers are oil the hooks.

The f-iresent invention provides-a means whereby the etl'ect of the low resistance ol the teiephonc receiver coils is neutralized and the magneto currents will therefore suflicien tlv energize the signal bell coils even when the receivers are oil the hooks and consequently whether the receivers be on the lilies and without in any manner changing the structure of the ordinary telephone set or requiring changes in the connections which could only he made by a person skilled in the installation of telephone lines.

The invention includes a suitahlc condenser ot a capacity )roperly chosen so as to be readily traversed iy the speaking currentbut which is practically impervious to the signal Current so that when the telephone is oil the hook the signal currents will no longer lind a path of low resistance through the telephone coils but will traverse the hell coils the same as it does when the receiver is on the hook and thci eby cut out ol the circuit Since the saving ol' battery is important in rural lines, and since it is advisable to provide the capacity ncccssary in the l'orni of a condenser scparato from the ordinary telephone set so as to be readily inserted in an ordinarytelephone line already installed, it is customary to inclosc a suitable condenser in a case and in the same case provide a. switch or pine; cut out [or the transmitter battery; thus in the practical embodiment of the present invention, there is provided a means which maybe readily included in telcphone lines already installed without change in said lines l'or the inclusion therein of both the necessary capacity and the cut out for the transmitter battery.

The invention will be best understood from a consideration of the following detail description taken in eoi'inection with the ac.- ('()lll])tiii:flll, drawings forming a partof this specification, in which drawings, Figure l. is a plan view ol' the attachment con- Hlltlltillg the subject matter of the present invention with the cover of the ease rcniovcd. Fig. 2 is a-diagrain showing the application of the invention to an ordinary tel"- phone line. v

' l'tcl'erring to the drawings, there is shown a suitable casing 1 in which is mounted a condenser 2 of proper capacity to prevent the passage of the magneto current through the coil of the ordinary telephone receiver which is indicated at 3 in Fig. 2.

ried by the case 1. I another binding post 8 which is connected to the other side of the condenser by a condue' tor 9.

The casing 1 is divided in its interior in two bolts 11*12 carrying at the ends remotei from the chamber inclosing the condenser 2, each a spring plate 13 the two spring plates being in parallel relation and close to each other and having their free ends out-turned as indicated at 14. Passing through one end of the casing 1 into the chamber containing the spring plates 1 3 is a rod 15having its inner end so located as to be readily inserted botween the plates 13 and electrically bridge the same, the said rod 15 being made of metal. The outer end of this rod is provided with an insulating button or handle 16 and on the rod within the casing is unadjustablc sleeve 17 preventing the rod from falling out of the casing and also acting as a stop for preventing the movement of the free or inner end of the rod between the spring members 13 to too great an extent, the adjustable collar 17 engaging the flaring portions 14 of said spring members when the free end of the rod is pushed in between said spring members.

In Fig. 2 the transmitter battery is indicated diagrammatically at 18, and outside of the casing 19 of the subscribers telephone set. it will be understood however, that this battery is located within the casing and is only shown outside thereof for illustrative purposes. The terminals of the battery and transmitter circuit are connected by conductors 20 and 21 to the screws 11 and 12 respectively so that the battery circuit of the transmitter isbrought to the spring members 13-13 as terminals oi such circuit, and this circuit maybe completed at will by moving the conducting rod 15 in between the spring members 13 and may be broken at will by pulling the rod 1'5 out of contact with these two spring members 13. By this means the battery 18 may be cut out of action when a subscriber is listening to an incoming message andmay be again coupled up for action when the subscriber desires to transmit a message over the line.

In Fig. 2 the transmitter is indicated at 22, and the telephone hook'is indicated at 23 while the signal bells-are indicated at 24 and are of thetype responsive to magneto produced alternating current transmitted over the line in the usual manner.

The subscribers telephone set -more or less diagrammatically represented in Fig. 2

1 is to be considered as of the ordinary type. and need not diller 1n any particular trom the conductor 6 leads to a binding post 7 car- 5 This case 1 also carries that ordinarily usedmi rural and other lines. This telephone set is connected up in the usual manner in the line wires 25' 26.

in installing the attaclhnent in the ordi- I nary telephone line and )articularly multiparty lines found in rura districts, the conducting cord of the receiver 3 which in t 1g. 2 is represented by the two conductors 27 and f. ZQ is disconnected from the terminals of the subscribers set, which terminals are represented in rig. 2 at 29 and thcends of these conductors 27 and 28 are connected up to the two binding posts 7 and 8 of the altaehnient which is preferably secured at any convenient point exterior to the telephone set of the subscriber, say at a convenient place on the wall within the reach otdhc person talking or at any other convenient point. The two conductors I] and (S are connected to the respective terminals 29, and the two conductors 2t) and '21 coming from the terminals 13 under the control of the bridging plug 15 are connected up in series with the transmitter battery 1Nv Suppose now that. a signal comes over the line in the usual manner, assuming that the receiver 3 is in pro )0! place upon the hook 23. This signal will operate the bells 21 and as is usually the case will be heard by all the SUbSCI'll'JOlS upon the particular inulliarly line. It is quite 'customary for dillcrent subscribers, curious to know what is going on over the line to remove their lelcphone receivers from the hooks 23 in order to listen to the conversation passing over the line, and assoon as the signal is heard some subscribers remove their telephone receivers at once from the ht'ioks. it often transpires that the called subscriber does not respond promptly! and it is necessary to send another call and perhaps two or threc' calls extra. So long as all the telephone receivers remain upon their respective hooks the signals are transmitted over the line without. dilliculty, since the only path for the magneto current is then through the signal bell coils, but as soon as one 'or more of the receivers are removed from their hooks then there is introduced into the line the receiver coils which offer suchlow resistance to the current produced by the impossible to repeat the. call so long as the telephone receivers remain oil' the hooks. Again, from carelessness users do not always replace the telephone receivers on the hooks and it is then practically impossible to call up those same subscribers over the line, thus often times cutting the entire line out of use much to the annoyance and loss of the other subscribers.

With the condenser 2 introduced into the circuit with the receiver coil whc'nthe said receiver is oil the hook, the low resistance magneto that it is practically path due to the introduction of the receiver coil in the line is neutralized tosuchan exwill respond to such transmitted currents,

tent that erative currents sent over the line from t e magneto generator will flow through the bell coils and the signal bells The introduction of the condenser does not interfere with the transmission speech impulses since theccondenser is freely perv1ous to alternating currents of the talking circuit, in fact the condenser may aid in a measure in reducing the impedance to the talking cur rent of tlie'receiver coil, and so permit the "passage over the line of moreintens'e talking currents than would otherwise be the case. The introduction of the condenser is in no Wise harmful to the talking circuit but under 'ordinary conditions is beneficial thereto.

When the telephone receiver 3 is in use and the operator wishes to listen without keeping the battery of the transmitter in cir cuit, the button 16 is grasped and the bridg-' ing pin 15 is withdrawn from between the sprlng terminals 13;' When it is desired to talk over the circuit then the bridging pin 15 v is pushed in between'the terminals 13 and the battery circuit to the transmitter is thereby completed. "Of course, when the receiver is placed back on the hook 23 the batter prising a suitable casing, a condenser housed therein, means for coupling the condenser up in series with a telephone receivencontact terminals also within the casing, a bridging member for the said contact terminals accessible from the exterior of the easing at the end remote from the condenser, and conductors leading from the said contact terminals and adapted to be connected up in the battery circuit of the telephone set.

2. An attachment for telephone sets comprising a suitable casing, a condenser housed therein, means for coupling the condenser up in series with a telephone receiver, spring contact terminals also within. the casing, a bridging member for said contact terminals comprising ,a rod extending and slidable throughthe end of the casing remote from the condenser, the outer end of the rod being provided with an insulating handle, and an adjustable collar on the rod Within the casing, and conductors leading from the said contact terminals anil adapted to be connect ed up in the battery circuit ofthe telephone set. I In testimony that I claim the foregoing as my own, I have hereto aliiXed my signature in the presence of two witnesses.

RICHARD E. PEDLGO. Witnesses:

E. S. WELLS, S. O. HICKMAN. 

